Variable valve timing mechanism

ABSTRACT

Embodiments of the disclosure provide variable valve timing (VVT) mechanisms. A VVT mechanism according to the disclosure can include: a lever having a first end, a second end, and a fulcrum positioned therebetween; a length-adjustable push rod coupled to the first end of the lever and including an actuator therein; a rod valve coupled to the second end of the lever, the rod valve being configured to open and close an intake valve of an engine system based on a movement of the lever; and an engine control unit (ECU) operatively connected to the actuator of the length-adjustable push rod, wherein the ECU adjusts a length of the length-adjustable push rod based on an operating condition of the engine system. In addition or alternatively, the ECU can control an amount of cushioning fluid for the valves to affect the rate at which the intake valve opens or closes.

BACKGROUND OF THE INVENTION

The disclosure relates generally to variable valve timing (VVT) mechanisms, such as those used in a variable inlet valve closure (VIC) mechanisms of an internal combustion engine.

Combustion engines typically combust a carbonaceous fuel, such as natural gas, gasoline, diesel, and the like, and use the corresponding expansion of high temperature and pressure gases to apply a force to certain components of the engine, e.g., a piston within a cylinder, to move the components over a distance. Each cylinder may include one or more valves that open and close to provide combustion of the carbonaceous fuel and release of exhaust. For example, an intake valve may direct an oxidizer such as air into the cylinder, which is then mixed with fuel and combusted. Combustion fluids, e.g., hot gases, may then be directed to exit the cylinder via an exhaust valve. Accordingly, the carbonaceous fuel is transformed into mechanical motion, useful in driving a load (e.g., a generator that produces electric power). In traditional configurations, timing of opening and closing the intake and exhaust valves during operation of the combustion engine may be monitored and estimated to detect various operating events and conditions (e.g., peak firing pressure) of the combustion engine.

As internal combustion engines are designed and/or modified to meet nitrogen oxide (NO_(x)) emissions standards, a designer may wish to keep other aspects of performance, such as efficiency and/or noise (also known as “knocking”), in parity with existing engines. Some combustion engines may operate using a thermodynamic process known as the “Miller cycle,” in which an air intake valve remains open for at least a portion of the engine's compression stroke. In the case of a Miller cycle combustion engine, changes in operating characteristics to comply with NO_(x) emissions standards can affect the start-up time and transient response (collectively, “transient-state operation”) of the engine, especially in low-temperature start conditions. Variable intake valve closure (VIC) mechanisms represent one approach for maintaining efficiency and reducing noise in this situation. Conventional VIC mechanisms may operate using a piston valve, which can include a rod valve positioned inside a cylinder for controlling the flow of air from the intake valve into the combustion chamber, e.g., during compression in a Miller cycle process. Though this type of mechanism can cause an advantageous delayed or early closure of the valve, the valve may nevertheless remain in a completely open (i.e., “lift”) position for the same amount of time as a conventional valve.

BRIEF DESCRIPTION OF THE INVENTION

A first aspect of the present disclosure provides a variable valve timing (VVT) mechanism including: a lever having a first end, a second end, and a fulcrum positioned therebetween; a length-adjustable push rod coupled to the first end of the lever and including an actuator therein; a rod valve coupled to the second end of the lever, the rod valve being configured to open and close an intake valve of an engine system based on a movement of the lever; and an engine control unit (ECU) operatively connected to the actuator of the length-adjustable push rod, wherein the ECU adjusts a length of the length-adjustable push rod based on an operating condition of the engine system.

A second aspect of the present disclosure provides a VVT mechanism including: a lever having a first end, a second end, and a fulcrum positioned therebetween; a rod valve coupled to the second end of the lever, the rod valve being configured to open and close an intake valve of an engine system based on a movement of the lever; a mechanical damping system including: a fluid chamber positioned between the rod valve and the second end of the lever, the fluid chamber being fluidly connected to a fluid source, and a fluid valve positioned between the fluid chamber and the fluid source; and an engine control unit (ECU) operatively connected to the fluid valve, wherein the ECU adjusts a position of the fluid valve based on an operating condition of the engine system.

A third aspect of the present disclosure provides a VVT mechanism including: a lever having a first end, a second end, and a fulcrum positioned therebetween; a length-adjustable push rod coupled to the first end of the lever and including an actuator therein; a rod valve coupled to the second end of the lever, the rod valve being configured to open and close an intake valve of an engine system based on a movement of the lever; and a mechanical damping system including: a fluid chamber positioned between the rod valve and the second end of the lever, the fluid chamber being fluidly connected to a fluid source, and a fluid valve positioned between the fluid chamber and the fluid source; and an engine control unit (ECU) operatively connected to the actuator and the fluid valve, wherein the ECU adjusts a length of the length-adjustable push rod and a position of the fluid valve based on an operating condition of an engine system including the intake valve therein.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various embodiments of the invention, in which:

FIG. 1 shows a cross-sectional view of a system including a conventional Miller cycle combustion engine.

FIG. 2 shows a cross-sectional view of a variable valve timing (VVT) mechanism according to embodiments of the present disclosure.

FIG. 3 shows a cross-sectional view of a VVT mechanism according to embodiments of the present disclosure.

FIG. 4 provides a schematic view of an illustrative environment including an engine control unit (ECU) of a VVT mechanism according to embodiments of the present disclosure.

FIG. 5 provides an illustrative plot of valve position “s” versus time “t” during operation of a VVT mechanism according to embodiments of the present disclosure.

It is noted that the drawings of the invention are not necessarily to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present disclosure relate generally to variable valve timing mechanisms, e.g., for internal combustion engines such as Miller cycle combustion engines. A variable valve timing (VVT) mechanism according to the present disclosure can include a lever with opposing first and second ends, and with a fulcrum positioned therebetween. A length-adjustable push rod, which includes an actuator therein for varying the length of the length-adjustable push rod, can be coupled to the first end of the lever. A rod valve can be coupled to the second end of the lever, with the fulcrum of the lever separating the rod valve from the length-adjustable push rod. The rod valve can open and close an intake valve of an engine system based on movement of the lever, e.g., in response to a linear movement of the length-adjustable push rod. An engine control unit (ECU) can be operatively connected to the actuator of the length-adjustable push rod. The ECU can adjust the length-adjustable push rod (i.e., extend and/or retract its length via the actuator) based on an operating condition of the engine system. More specifically, the ECU can selectively adjust the length of the length-adjustable push rod coincident with an opening or closing motion of the rod valve during start-up, transient, and/or turn-down operation (collectively, “transient-state operation”) of an engine. In addition, the ECU can selectively disable its adjustment of the push rod, e.g., by maintaining the length-adjustable push rod at a constant length during steady-state operation of the engine.

Spatially relative terms, such as “inner,” “outer,” “underneath,” “below,” “lower,” “above,” “upper,” “inlet,” “outlet,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “underneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Turning to the drawings, FIG. 1 illustrates a partial cross-sectional view of a conventional engine system 10. As described in detail below, engine system 10 can be provided as, e.g., a reciprocating internal combustion engine with one or more combustion chambers 12 (e.g., one, five, ten, twenty, or more combustion chambers 12). A gas supply 14 can provide a pressurized oxidant, such as air, oxygen, oxygen-enriched air, oxygen-reduced air, or any combination thereof, to combustion chamber(s) 12. Combustion chamber(s) 12 can also receive a fuel, e.g., a liquid and/or gaseous fuel introduced, for example, through a carburetor, from a fuel supply 18, such that a fuel-air mixture ignites and combusts within each combustion chamber 12. The hot pressurized combustion gases can cause a piston 20 adjacent to each combustion chamber 12 to move linearly within a cylinder 22 and convert pressure exerted by the gases into a rotating motion, which moves a pin 24 and thereby rotates a shaft 25. Further, shaft 25 may be coupled to a load (not shown), which is powered via rotation of shaft 25. For example, shaft 25 can be mechanically coupled to any suitable device that may generate power via the rotational output of system 10, such as an electrical generator. Additionally, although the following discussion refers to air as an example, any suitable supply of oxidant may be employed as a substitute for gas supply 14 with the disclosed embodiments. Similarly, fuel provided from fuel supply 18 may be any suitable gaseous fuel, such as natural gas, associated petroleum gas, propane, biogas, sewage gas, landfill gas, coal mine gas, for example.

Gas from gas supply 14 and fuel from fuel supply 18 can enter combustion chamber 12 through an inlet 28. The ability for air and fuel to travel through inlet 28 can be controlled, e.g., by an intake valve 28 which can be provided in the form of a rod valve. A rod valve generally includes any and all valves structured with a rod and closing element (e.g., a block, plunger, etc.) at one end thereof. In addition, engine system 10 can include an outlet 32 for expelling exhaust from combustion chamber 12. The ability for exhaust to exit combustion chamber 12 through outlet 32 can be controlled by, e.g., an outlet valve 34. Outlet valve 34 can be provided as a rod valve and/or as any other currently known or later developed instrument for controlling the flow of exhaust fluids through a region such as outlet 32. As discussed elsewhere herein, embodiments of the present disclosure can include and/or be mechanically coupled to valves such as intake valve 30 and/or outlet valve 34 to affect the operation of internal combustion engines, such as those provided in engine system 10.

Engine system 10 disclosed herein may be adapted for use in stationary applications (e.g., in industrial power generating engines) or in mobile applications (e.g., in cars or aircraft). System 10 may include a two-stroke engine, three-stroke engine, four-stroke engine, five-stroke engine, or six-stroke engine. Engine 10 may also include any number of combustion chambers 12, pistons 20, and associated cylinders 26. For example, in certain embodiments, system 10 may include a large-scale industrial reciprocating engine having four, six, eight, ten, sixteen, twenty-four or more pistons 20 reciprocating in respective cylinders 26. In some such cases, the cylinders 26 and/or the pistons 20 may have a diameter of between approximately 13.5-34 centimeters (cm). In some embodiments, the cylinders 26 and/or pistons 20 may have a diameter of between approximately 10-40 cm, 15-25 cm, or about 15 cm. Engine system 10 may generate power ranging from 10 kW to 10 MW. In some embodiments, engine system 10 may operate at less than approximately 1800 revolutions per minute (RPM). In other embodiments, engine system 10 may operate at less than approximately 2000 RPM, 1900 RPM, 1700 RPM, 1600 RPM, 1500 RPM, 1400 RPM, 1300 RPM, 1200 RPM, 1000 RPM, 900 RPM, or 750 RPM. In other embodiments, engine system 10 may operate between approximately 750-2000 RPM, 900-1800 RPM, or 1000-1600 RPM. In still other embodiments, engine system 10 may operate at approximately 1800 RPM, 1500 RPM, 1200 RPM, 1000 RPM, or 900 RPM. Example embodiments of system 10 may include General Electric Company's Jenbacher Engines (e.g., Jenbacher Type 2, Type 3, Type 4, Type 6 or J920 FleXtra) or Waukesha Engines (e.g., Waukesha VGF, VHP, APG, 275GL), for example.

Turning to FIG. 2, a variable valve timing (VVT) system 100 according to embodiments of the present disclosure is shown. As described herein, VVT system 100 can influence the operation of embodiments of engine system 10 (FIG. 1), e.g., in the form of a Miller cycle internal combustion engine. VVT system 100 can include a timing mechanism 102 and/or a cushioning mechanism 104. Although each timing and/or cushioning mechanism 102, 104 can be embodied as a separate device, it is understood that components of timing mechanism 102 can be included as part of cushioning mechanism 104 and vice-versa. As is discussed herein, timing mechanism 102 can selectively extend or reduce the time period in which an intake valve 28 (FIG. 1) is in an open position by providing an additional opening force against intake valve 28 and/or opposing a closing motion of intake valve 28. The additional force provided by timing mechanism 102 can originate from, e.g., an actuator mechanically coupled to components for opening and/or closing intake valve 28. Cushioning mechanism 104 can further extend the time period in which intake valve 28 remains in an open position, e.g., by selectively providing additional frictional force against intake valve 28 as it closes. In addition, it is understood that timing mechanism 102 can be removed and/or substituted for another mechanism to provide an accelerated closure of intake valve 28. Although delayed valve closure is discussed by example herein, it is understood that embodiments of the present disclosure can also be applied to generate an accelerated closure of the valve.

As discussed herein, cushioning mechanism 104 can supply cushioning fluids to a moving component of intake valve 28, thereby creating an opposing frictional force. The cushioning fluids can be supplied, e.g., prior to or during a closing motion of intake valve 28, before being depleted to reduce friction against intake valve 28 during other strokes. In any event, timing mechanism 102 and/or cushioning mechanism 104 can be selectively enabled and disabled, such that each mechanism 102, 104 adjusts the closure timing of intake valve 28 during a particular operating condition of engine system 10, e.g., transient-state operation.

Referring to timing mechanism 102, a lever 106 thereof can include a fulcrum 108 positioned between a first end 110 of lever 106 and an opposing second end 112 of lever 106. Fulcrum 108 can be mounted on or coupled to an external structure (not shown) while permitting rotational movement of lever 106 along direction R in a positive direction (i.e., in the same direction as the arrowhead orientation) and/or a negative direction (i.e., opposite the arrowhead orientation). During operation, lever 106 can rotate at least partially about fulcrum 108, thereby causing translational movement of a length adjustable push rod 114 relative to lever 106 (e.g., coupled to lever 106 proximal to first end 110) to yield a corresponding opening or closing of rod valve(s) 116 (coupled to lever 106 proximal to second end 112). Rod valve(s) 116 during operation can be a type of intake valve 28 (FIG. 1). Length adjustable push rod 114 can include an actuator 118 therein. Actuator 118 can be provided as any currently-known or later developed device for providing a variable length, volume, area, etc. For example, actuator 118 can be embodied as one or more of, e.g., a linear actuator, a piezoelectric actuator, a pneumatic actuator, a servo actuator, a nano actuator, a hydraulic actuator, a motor-driven actuator, and/or any other currently known or later-developed mechanism for adjusting a component length. Although actuator 118 is described by example herein as being capable of, e.g., extending or retracting movement, it is understood that different types of movement suited to a particular embodiment of actuator 118 can also be applicable and can yield the same effects. As such, the terms “extending,” “retracting,” etc., as applied to actuator 118 should not be given a limited interpretation. Actuator 118 in any case can be coupled to an engine control unit (ECU) 120 embodied as, e.g., a general-purpose component with engine control software thereon and/or a special-purpose hardware component. ECU 120 can adjust the length of length-adjustable push rod 114 by extending or retracting actuator 118 as described herein, e.g., to create an additional timing delay during the closure of a valve such as inlet valve 28 (FIG. 1).

An end of length-adjustable rod 114, distal to first end 110 of lever 106, can be mechanically coupled to a follower 122. Follower 122, in turn, include a bearing 124 which engages a cam lobe 126, e.g., by direct physical contact therebetween. Although follower 122 is shown in FIG. 2 as being in the form of a lever, other configurations are possible. For example, follower 122 can be provided in the form of stud-type follower or yoke-type follower. Cam lobe 126 can include at least one elongated portion for pressing against follower 122 as it rotates, e.g., substantially along the direction line L, thereby moving length-adjustable arm 114 relative to lever 106. Bearing 124 can be provided in the form of a roller bearing configured to roll against cam lobe 126 during rotation thereof (e.g., in the direction indicated with line L).

Referring to FIG. 3, a partial view of VVT system 100 and timing mechanism 102 is shown to illustrate features of length-adjustable rod 114. Length adjustable rod 114 can include a first member 128 and a second member 130 joined together by actuator 118. First or second member 128, 130 can include a sleeve 132 therein (shown by example in FIG. 3 to be within first member 128) for receiving actuator 118 in a retracted state. Sleeve 132 can include retention elements therein (e.g., threaded slots) for engaging actuator 118 (e.g., by way of threading thereon) in a desired position. Sleeve 132 can thereby cooperatively engage actuator 118 to hold actuator 118 in a fully extended, partially extended, or retracted position to thereby adjust the length of length-adjustable rod 114. A converter 134 can convert an electrical current into a mechanical force for moving actuator 118 within sleeve 132. Converter 134 can be embodied as any currently known or later-developed component for transforming a particular input into a mechanical output, and can be embodied as a component of one or more of the example embodiments of actuator 118 discussed elsewhere herein.

Returning to FIG. 2, VVT system 100 can also include cushioning mechanism 104, which can be provided as a damping mechanism of VVT system 100 or as a separate, independent device. Cushioning mechanism 104 can include a spring 136 positioned circumferentially about and in contact with the body of each rod valve 116. Spring(s) 136 in an equilibrium state can maintain rod valve(s) 116 in a closed position, such that air and/or fuel are substantially prevented from flowing through inlet 28. Movement of second end 112 of lever 106 in a downward direction can compress spring(s) 136 to move rod valve(s) 116 downward into an open position. The movement of rod valve(s) 116 into an open position can thereby permit a flow of fluids into combustion chamber(s) 12 through inlet(s) 28. A full compression of spring(s) 136 can displace rod valve(s) 116 by a corresponding distance “s_(L),” where each rod valve 116 is said to be in a fully open position, also known as a “lift” position.

Each rod valve 116 can extend through a fluid chamber 138 with damping fluids therein, e.g., pressurized fluids such as oil. The fluids within fluid chamber 138 can be provided from a fluid supply 140, and can create additional friction against rod valve(s) 116 to oppose an opening or closing motion of rod valve(s) 116. Although fluid supply 140 is shown by example in FIG. 2 as being a dedicated component, multiple alternative embodiments are contemplated. For example, fluid supply 140 can be embodied as an oil line of an engine, e.g., including and/or connected to fuel supply 18 (FIG. 1). In this situation, cushioning fluids can be routed to fluid chamber 138 from fluid supply 140 in the form of a bypass from the engine line. The bypass line which acts as fluid supply 140 can include a bypass line from the same engine system 10 (FIG. 1) controlled with VVT system 100, or can be routed from a different engine system. Fluids within fluid chamber 138 can be expelled through outlet(s) 139 therein, which may be selectively opened or closed by action of an outlet valve (not shown). As will be discussed herein, fluids from fluid supply 140 can be provided to and/or extracted from fluid chamber(s) 138 based on the position and movement of spring(s) 136 and/or the status of engine system 10 (FIG. 1). One or more fluid valves 142 can govern the ability for pressurized fluids of fluid supply 140 to flow into and/or out of fluid chamber(s) 138.

Turning to FIG. 4, example sub-components of ECU 120 are shown to illustrate the operation of ECU within VVT system 100 (FIG. 2) and timing or cushioning mechanisms 102 (FIGS. 2, 3), 104 (FIG. 2) therein. FIG. 4 depicts an illustrative environment 200 in which ECU 120 is placed in communication with one or more position sensors 144, one or more dynamic sensors 146, actuator 118 for controlling a length of length-adjustable rod 114 (FIGS. 2, 3), and/or valve(s) 142 for controlling the flow of fluids from fluid supply 140 (FIG. 2) according to embodiments. To this extent, environment 200 includes ECU 120 for performing processes and imparting electrical commands to control actuator 118, valve(s) 142, position sensor(s) 144, and/or dynamic sensor(s) 146 along with any associated systems and tools. Although actuator 118, valve(s) 142, position sensor(s) 144, and dynamic sensor(s) 146 are shown by example in FIG. 4, it is understood that environment 200 with ECU 120 can be used with only one or multiple embodiments of the present disclosure discussed herein, including without limitation one or more combustion chamber(s) 12.

ECU 120 is shown including a processing component 204 (e.g., one or more processors), a memory 206 (e.g., a storage hierarchy), an input/output (I/O) component 208, an I/O device 209 (e.g., one or more I/O interfaces and/or devices), and a communications pathway 210. In general, processing component 204 executes program code, such as an actuator control system 212 and/or a valve control system 214, which is at least partially fixed in memory 206. While executing program code, processing component 204 can process data, which can result in reading and/or writing transformed data from/to memory 206 and/or I/O device 209 for further processing. Pathway 210 provides a communications link between each of the components in ECU 120. I/O component 208 can comprise one or more human I/O devices, which enable a human or system user 216 to interact with the ECU 120 and/or one or more communications devices to enable user(s) 216 to communicate with ECU 120 using any type of communications link. To this extent, actuator and valve control systems 212, 214 can manage a set of interfaces (e.g., graphical user interface(s), application program interface, etc.) that enable user(s) 216 to interact with actuator and/or valve control systems 212, 214. Further, one or both of actuator control system 212 and/or valve control system 214 can manage (e.g., store, retrieve, create, manipulate, organize, present, etc.) data, such as system data 218 (including measured or recorded positions, acoustic outputs, etc.) using any solution.

ECU 120 is shown as including an actuator control system 212 which allows ECU 120 to adjust the length of length-adjustable rod 114 by way of actuator 118. ECU can also include valve control system 214 which makes ECU 120 operable to direct and operate valve(s) 142. In operation, actuator and valve control systems 212, 214 can issue electrical commands, which in turn may be converted into mechanical actions (e.g., an action of adjusting actuator 118, opening and closing one or more valves 142) in response to particular conditions. The conditions for adjusting actuator 118 and/or valves 142 can include, e.g., engine system 10 (FIG. 1) undergoing a transient-state or steady-state operation.

In any event, ECU 120 can comprise one or more general-purpose or specific-purpose computing articles of manufacture (e.g., computing devices) capable of executing program code, such as actuator or valve control systems 212, 214, installed thereon. As used herein, it is understood that “program code” means any collection of instructions, in any language, code or notation, that cause a computing device having an information processing capability to perform a particular function either directly or after any combination of the following: (a) conversion to another language, code or notation; (b) reproduction in a different material form; and/or (c) decompression. To this extent, the actuator or valve control systems 212, 214 can be embodied as any combination of system software and/or application software.

Further, the actuator and/or valve control systems 212, 214 can each be implemented using a respective set of modules 220. In this case, a module 220 can enable ECU 120 to perform a set of tasks used by actuator and/or valve control system(s) 212, 214, and can be separately developed and/or implemented apart from other portions of actuator and/or valve control system(s) 212, 214. One or more modules 220 of memory 206 can display (e.g., via graphics, text, sounds, and/or combinations thereof) a particular user interface on a display component such as a monitor. When fixed in memory 206 of ECU 120 that includes processing component 204, a module is a substantial portion of a component that implements the functionality. Regardless, it is understood that two or more components, modules and/or systems may share some/all of their respective hardware and/or software. Further, it is understood that some of the functionality discussed herein may not be implemented or additional functionality may be included as part of ECU 120.

When ECU 120 comprises multiple computing devices, each computing device may have only a portion of actuator and/or valve control system(s) 212, 214 fixed thereon (e.g., one or more modules 220). In addition, embodiments of the present disclosure can include multiple ECUs 120 each with a respective one of actuator control system 212 or valve control system 214 thereon. However, it is understood that ECU 120, actuator control system 212, and/or valve control system 214 are only representative of various possible equivalent computer systems that may perform a process described herein. To this extent, in other embodiments, the functionality provided by ECU 120, actuator control system 212, and/or valve control system 214 can be at least partially implemented by one or more computing devices that include any combination of general and/or specific purpose hardware with or without program code. In each embodiment, the hardware and program code, if included, can be created using standard engineering and programming techniques, respectively.

Regardless, when ECU 120 includes multiple computing devices, the computing devices can communicate over any type of communications link. Further, while performing a process described herein, ECU 120 can communicate with one or more other computer systems using any type of communications link. In either case, the communications link can comprise any combination of various types of wired and/or wireless links; comprise any combination of one or more types of networks; and/or use any combination of various types of transmission techniques and protocols.

It is understood that aspects of the invention further provide various alternative embodiments. For example, in one embodiment, ECU 120 can adjust a delay period in which rod valves 118 remain in a lift position, and/or a closing speed of rod valves 118, e.g., by adjusting the length of length-adjustable rod 114 and/or opening and closing valves 142. In other embodiments, operation of VVT system 100 can include manual use of ECU 120 (e.g., operation by a technician) and/or automated use by the intervention of one or more computer systems operatively connected thereto to provide, e.g., one or more of the technical effects discussed herein. It is thus understood that ECU 120 may serve technical purposes in other settings beyond general operation, including without limitation: inspection, maintenance, repair, replacement, testing, etc.

Actuator and valve control systems 212, 214 can, together or separately, be provided in the form of a computer program fixed in at least one computer-readable medium, which when executed, enables ECU 120 to manipulate length-adjustable rod 114 and/or valves 142. To this extent, the computer-readable medium includes program code which implements some or all of the processes and/or embodiments described herein. It is understood that the term “computer-readable medium” comprises one or more of any type of tangible medium of expression, now known or later developed, from which a copy of the program code can be perceived, reproduced or otherwise communicated by a computing device. For example, the computer-readable medium can comprise: one or more portable storage articles of manufacture; one or more memory/storage components of a computing device; paper; etc.

Turning briefly to FIG. 5, an illustrative plot of spring compression “s” versus time “t” during operation is shown to better illustrate the function of ECU 120. During conventional operation (e.g., without adjustment of length-adjustable push rod 114), rod valve(s) 116 can move from a completely closed to a completely open (lift) position S_(L), before closing at a time to as noted by the solid trend line. However, during particular operating phases (e.g., transient-state operation of engine system 10 (FIG. 1)), an operator may wish to extend the time period in which rod valve(s) 116 are in the completely open position, e.g., by a “delay” time expressed as the difference between to and one of times t₁, t₂, t₃ (shown with phantom lines). To achieve this effect, ECU 120 can selectively extend actuator 118 before or during compression of spring(s) 136, thereby maintaining rod valve(s) 116 in a lift position for a longer period. In addition or alternatively, ECU 120 can adjust valve(s) 142 to provide a cushioning effect against closing rod valve(s) 116. Although period of delay are depicted in FIG. 5, it is understood that embodiments of the present disclosure can also be adapted for accelerating valve closure.

Referring to FIGS. 2 and 4 together, ECU 120 can receive an indication, e.g., through I/O component 208, of whether engine system 10 (FIG. 1) is presently undergoing transient-state or steady-state operation. The indication can be provided directly in the form of an electrical signal or input from user(s) 216, and/or can include operational data (e.g., a load or operating speed of engine system 10) from which valve and/or actuator control systems 212, 214 can derive the operation condition of engine system 10 (e.g., based on the load or operating speed of engine system 10 exceeding a predetermined threshold). The present operating state of engine system 10 can be stored, e.g., as a form of system data 218. ECU 120 can selectively enable or disable the extension and/or retraction of length adjustable push rod 114 based on other characteristics of engine system 10. Where the operating condition of engine system 10 is a steady-state operating condition, ECU 120 can maintain length-adjustable push rod 114 and/or valves 142 in a static condition such that engine system 10 operates with a predetermined amount of intake valve delay (e.g., time to of FIG. 5).

During transient-state operation of engine system 10 (FIG. 1), ECU 120 can adjust actuator 118 to extend length-adjustable push rod 114 and/or adjust valve(s) 142 to control the amount of fluid in fluid chamber(s) 138. The adjustment of length-adjustable push rod 114 and/or valve(s) 142 can occur, e.g., only during particular phases or strokes of engine system 10. For example, ECU 120 can adjust length-adjustable rod 114 and/or valve(s) 142 prior to and/or during a closing motion of rod valve(s) 116, and/or expansion of spring(s) 136. Position sensor 144 can measure the position of rod valve(s) 116 and/or spring(s) 136 in real time to determine whether rod valve(s) 116 are in an open position, a closed position, and/or are undergoing opening or closing motions. In response to identifying a closing motion from an open position, as discussed in further detail herein, ECU 120 can adjust length-adjustable rod 114 and/or valve(s) 142 to increase the amount of delay before of rod valve(s) 116 close (e.g., selectively yielding a delay time of t₁, t₂, t₃, t₄, t₅ (FIG. 5)).

ECU 120, with timing mechanism 102, can adjust a time period in which rod valve(s) 116 remain in an open position. For example, position sensor(s) 144 can be operatively connected to ECU 120 and configured to detect a compression of spring(s) 136 and/or a rotational position of cam lobe 126. Each position sensor 144 can be embodied as one or more of, e.g., a laser sensor, a piezoelectric sensor, a resistance-based position sensor, an optical position sensor, a fiber-optic position sensor, etc. Position sensor 144 can detect a compression or expansion of spring(s) 136 directly or indirectly based on the quantities being measured. Where position sensor 144 measures a compression indicative of spring(s) 136 being in a lift position (e.g., compression by distance s_(L)) and transmits this measurement to ECU 120 (e.g., in the form of encoded electrical signals), ECU 120 can adjust length-adjustable push rod 114 (e.g., by extending or retracting actuator 118) based on one or more operating characteristics of engine system 10 (FIG. 1).

Where position sensor 144 is connected to ECU 120 and detects a compression of spring(s) 136, modules 220 of actuator control system 212 can instruct ECU 120 to extend actuator 118 to increase the length of length-adjustable push rod 114 for a predetermined time. Thereafter, modules 220 of actuator control system 212 can instruct ECU 120 to retract actuator 118 and allow spring(s) 138 to decompress, thereby closing rod valve(s) 116. In addition or alternatively, position sensor(s) 144 can indirectly detect a compression of spring(s) 136 based on a rotational position of cam lobe 126. For instance, cam lobe 126 can include a marker for indicating a position where a cam lobe 126 actuates follower 122 (e.g., by a lobe portion contacting bearing 124) to cause compression of spring(s) 136. The position of cam lobe 126 can thereby indicate whether spring(s) 136 are expanding or being compressed.

ECU 120 can also control the operation of cushioning mechanism 104 to extend the time needed for rod valve(s) 116 to close. For example, ECU 120 can increase or decrease the amount of fluids in fluid chamber(s) 138 by opening and closing valves 142, e.g., during transient operation of engine system 10 (FIG. 1). Cushioning mechanism 104, more specifically, can serve as a mechanical damping system during a closing (e.g., expanding) motion of spring(s) 136 to prolong the time in which rod valve(s) 116 are in an open position. To provide this effect, modules 220 of valve control system 214 can instruct ECU 120 to position valve(s) 142 in an at least partially-closed position, and cause fluids from fluid supply 140 to enter fluid chamber(s) 138. Additional fluid in fluid chamber(s) 138 can provide additional frictional force against the closing of rod valve(s) 116, thereby slowing down their closure. Modules 220 of valve control system 214 can determine whether rod valve(s) 116 are closing by way of position sensor(s) 144 as discussed elsewhere herein.

In addition or alternatively, VVT system 100 can include an acoustic sensor 146 operatively connected to ECU 120. Acoustic sensor 146 can be provided in the form of any currently known or later developed instrument for reading various types of noise and/or acoustic activity including, without limitation, a microphone, a vibration sensor, a knock sensor, etc.

It should be understood that ECU 120 can apply any number of currently known or later-developed techniques, e.g., analysis of acoustic frequencies, amplitudes, wavelengths, etc., to inputs from acoustic sensor 146 to detect a closing movement of rod valve(s) 116. In some embodiments, the input to acoustic sensor 146 may be filtered via a high-pass filter, a low-pass filter, or a band-pass filter to attenuate portions of the signal having frequencies uncharacteristic of the operating event. The particular filter applied to the noise signal may depend on the operating condition being monitored (e.g., one filter for transient-state operations, and/or another for steady state operation). Pursuant to these analyses and/or similar processing of acoustic inputs, ECU 120 can determine one or more operating conditions of engine system 10 (FIG. 1), based on the inputs from acoustic sensor 146, to determine whether engine system 10 presently operates in startup, transient, or steady state, e.g., by way of a look-up table, formula, etc., for determining a particular operating conditions (e.g., transient-state, and/or steady state operation). In an alternative embodiment, acoustic sensor 146 can be provided as a component and/or module of ECU 120. Example techniques for determining whether an engine operates in a startup mode, a transient mode, a steady-state mode, etc., are described generally in U.S. patent application Ser. Nos. 14/609,416 and 15/680,863, either or both of which can be adapted for use with ECU 120.

Regardless of the analysis used, ECU 120 together with acoustic sensor 146 can identify an opening and/or closing of rod valve(s) 116 based on the similarity of inputs to acoustic sensor 146 to predetermined acoustic profiles. Where ECU 120 senses a closing motion of rod valve(s) 116 (e.g., an expansion of spring(s) 136), ECU 120 can open valve(s) 142 to allow a flow and/or replenishment of pressurized fluids from fluid supply 140 to pressurized chamber(s) 138 to dampen the closing of rod valve(s) 116 as described elsewhere herein. The acoustic analysis of engine system 10 (FIG. 1) can be provided as an addition and/or alternative to the position analysis of rod valve(s) 116 and/or cam lobe 126 with position sensors 144 described elsewhere herein.

Embodiments of the present disclosure can provide several technical and commercial advantages. For example, embodiments of the present disclosure can be operable to extend the delay period in which an intake valve of an engine system, such as those employing a Miller cycle, can remain in an open position to increase the amount of air/fuel intake during startup and/or transient state operation. In addition, embodiments of the present disclosure can be selectively enabled and/or disabled based on operating conditions of the engine, e.g., to avoid prolonging the open period of an intake valve during steady state operation. Prolonging the time in which an intake valve of a compression chamber is open under particular operating conditions can reduce the total amount of emissions while retaining a desired level of efficiency and/or acoustic output for an engine. These technical advantages can also provide related benefits to components operatively connected to the engine system, e.g., by further improving the performance and/or efficiency of a turbocharger system.

The apparatus and method of the present disclosure is not limited to any one particular gas turbine, combustion engine, power generation system or other system, and may be used with other power generation systems and/or systems (e.g., combined cycle, simple cycle, nuclear reactor, etc.). Additionally, the apparatus of the present invention may be used with other systems not described herein that may benefit from the increased operational range, efficiency, durability and reliability of the apparatus described herein. In addition, the various injection systems can be used together, on a single nozzle, or on/with different nozzles in different portions of a single power generation system. Any number of different embodiments can be added or used together where desired, and the embodiments described herein by way of example are not intended to be mutually exclusive of one another.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

The present disclosure may be embodied as a system, a method, and/or a computer program product. The computer program product may include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present invention.

The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire.

Computer readable program instructions for carrying out operations of the present invention may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++ or the like, and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program instructions may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present invention.

This written description uses examples to disclose the invention, including the best mode, and to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. 

What is claimed is:
 1. A variable valve timing (VVT) mechanism comprising: a lever having a first end, a second end, and a fulcrum positioned therebetween; a length-adjustable push rod coupled to the first end of the lever and including an actuator therein; a rod valve coupled to the second end of the lever, the rod valve being configured to open and close an intake valve of an engine system based on a movement of the lever; and an engine control unit (ECU) operatively connected to the actuator of the length-adjustable push rod, wherein the ECU adjusts a length of the length-adjustable push rod based on an operating condition of the engine system.
 2. The VVT mechanism of claim 1, wherein the length-adjustable push rod further includes a first member and a second member each coupled to an opposing end of the actuator, and wherein one of the first member and the second member further includes a sleeve for receiving the actuator therein.
 3. The VVT mechanism of claim 1, further comprising: a spring positioned circumferentially about the rod valve, and interposed between the second end of the lever and the intake valve of the engine system; and a position sensor operatively connected to the ECU, wherein the ECU further adjusts the length-adjustable push rod in response to detecting a compression of the spring.
 4. The VVT mechanism of claim 3, further comprising a cam lobe coupled to the length-adjustable push rod, wherein the position sensor measures a position of the cam lobe to detect the compression of the spring.
 5. The VVT mechanism of claim 1, further comprising a mechanical damping system coupled to the rod valve.
 6. The VVT mechanism of claim 1, wherein the intake valve comprises an air-intake valve of a Miller cycle combustion chamber.
 7. The VVT mechanism of claim 1, wherein the ECU further adjusts the length of the length-adjustable push rod to maintain the intake valve in an open position.
 8. The VVT mechanism of claim 1, wherein the operating condition of the engine system comprises one of a transient-state operation and steady-state operation, and wherein the ECU increases a length of the length-adjustable push rod in response to the engine system having the transient-state operation.
 9. A variable valve timing (VVT) mechanism comprising: a lever having a first end, a second end, and a fulcrum positioned therebetween; a rod valve coupled to the second end of the lever, the rod valve being configured to open and close an intake valve of an engine system based on a movement of the lever; a mechanical damping system including: a fluid chamber positioned between the rod valve and the second end of the lever, the fluid chamber being fluidly connected to a fluid source, and a fluid valve positioned between the fluid chamber and the fluid source; and an engine control unit (ECU) operatively connected to the fluid valve, wherein the ECU adjusts a position of the fluid valve based on an operating condition of the engine system.
 10. The VVT mechanism of claim 9, further comprising an acoustic sensor operatively connected to the ECU, wherein the ECU is further configured to open the fluid valve in response to the acoustic sensor detecting a closing movement of the rod valve.
 11. The VVT mechanism of claim 10, wherein the operating condition of the engine system comprises one of a transient-state operation and steady-state operation, and wherein the ECU adjusts the position of the fluid valve in response to the engine system having the transient-state operation.
 12. The VVT mechanism of claim 10, wherein the ECU is further configured to open the fluid valve in response to detecting the closing movement of the rod valve, and wherein a cushioning fluid entering the fluid chamber from the fluid source reduces a closing speed of the rod valve.
 13. The VVT mechanism of claim 9, further comprising a length-adjustable push rod coupled to the first end of the lever and including an actuator therein.
 14. The VVT mechanism of claim 9, wherein the intake valve comprises an air-intake valve of a Miller cycle combustion chamber.
 15. A variable valve timing (VVT) mechanism comprising: a lever having a first end, a second end, and a fulcrum positioned therebetween; a length-adjustable push rod coupled to the first end of the lever and including an actuator therein; a rod valve coupled to the second end of the lever, the rod valve being configured to open and close an intake valve of an engine system based on a movement of the lever; and a mechanical damping system including: a fluid chamber positioned between the rod valve and the second end of the lever, the fluid chamber being fluidly connected to a fluid source, and a fluid valve positioned between the fluid chamber and the fluid source; and an engine control unit (ECU) operatively connected to the actuator and the fluid valve, wherein the ECU adjusts a length of the length-adjustable push rod and a position of the fluid valve based on an operating condition of an engine system including the intake valve therein.
 16. The VVT mechanism of claim 15, wherein the length-adjustable push rod further includes a first member and a second member each coupled to an opposing end of the actuator, and wherein one of the first member and the second member further includes a sleeve for receiving the actuator therein.
 17. The VVT mechanism of claim 15, further comprising: a spring positioned circumferentially about the rod valve, and interposed between the second end of the lever and the intake valve of the engine system; and a position sensor operatively connected to the ECU, wherein the operating condition of the engine system includes a compression of the spring, and wherein the ECU adjusts a length of the length-adjustable push rod in response to the position sensor detecting a compression of the spring.
 18. The VVT mechanism of claim 17, further comprising a cam lobe coupled to the length-adjustable push rod, wherein the position sensor measures a position of the cam lobe to detect the compression of the spring.
 19. The VVT mechanism of claim 15, further comprising an acoustic sensor operatively connected to the ECU, wherein the ECU is further configured to open the fluid valve in response to detecting a closing movement of the rod valve.
 20. The VVT mechanism of claim 15, wherein the operating condition of the engine system comprises one of a transient-state operation and steady-state operation, and wherein the ECU increases a length of the length-adjustable push rod in response to the engine system having the transient-state operation. 